1. Field of the Invention
The present invention relates to a processing jig for holding an object processed by a processing apparatus.
2. Description of the Related Art
A flying-type thin-film magnetic head used for a magnetic disk drive and so on is generally made up of a slider and a magnetic head element provided at the trailing edge of the slider. The slider generally comprises a rail whose surface functions as a medium facing surface (an air bearing surface) and a tapered section or a step near the end on the air inflow side. The rail flies slightly above the surface of a recording medium such as a magnetic disk by means of air flow from the tapered section or step.
A thin-film magnetic head element generally used is a composite element made up of layers of an induction-type electromagnetic transducer for writing and a magnetoresistive (MR) element for reading.
In general, such thin-film magnetic heads are formed through cutting a wafer in one direction in which sections to be sliders (hereinafter called slider sections) each including a thin-film magnetic head element are aligned in a plurality of rows. A bar-like magnetic head material (hereinafter called a bar) made up of a row of slider sections is thereby formed. Processing such as lapping is performed on a surface of the bar to be the medium facing surface (hereinafter called the medium facing surface for convenience). The bar is then separated into individual sliders.
In general, in order to stabilize the output characteristic of a thin-film magnetic head, it is important to maintain the distance between the magnetic pole of the head and the surface of a recording medium at an extremely small specific value. It is therefore required in magnetic head processing that the flatness of the medium facing surface of the head precisely fall on a specific value so as to stabilize a flying amount and that the throat height and the MR height of the head fall within specific ranges. The throat height is the length (height) of the magnetic pole of an induction-type electromagnetic transducer between an end thereof located in the medium facing surface and the other end. The MR height is the length (height) between an end of the MR element located in the medium facing surface and the other end.
There are several methods for lapping the medium facing surface so as to achieve desired values of the throat height and MR height of a thin-film magnetic head. A method generally used and achieving high precision is the method that utilizes a processing jig having functions described later and a lapping apparatus having the function of automatically lapping while applying an appropriate load to the jig and deforming the bar bonded to the jig.
The processing jig used in this method comprises a main body fixed to the lapping apparatus, a retainer that is long in one direction for retaining a bar, and a plurality of load application sections, coupled to the retainer, to each of which a load is applied for deforming the retainer. The shape of the retainer is a narrow and long beam that is bent with an application of external force. An external force being applied to the load application sections of the jig, the retainer is bent. The bending of the retainer causes bending of the bar held by the retainer.
A method of lapping a bar using the jig will now be described. In this method, the bar is fixed to the retainer of the jig with an adhesive and the like so that the surface of the bar to be lapped faces outside.
Next, the values of the throat height and MR height of each magnetic head element in the bar fixed to the jig are determined through an optical or electrical method. The deviation of the determined values from the target values, that is, the amounts of lapping required, are calculated.
Of the sections to be lapped corresponding to the magnetic head elements in the bar, a section that requires a greater amount of lapping than the other sections needs to be more lapped. Therefore, the bar is deformed by applying loads to the load application sections so that the surface to be lapped of the section is made convex. On the other hand, a section that requires a smaller amount of lapping than the other sections needs to be less lapped. Therefore, the bar is deformed by applying loads to the load application sections so that the surface to be lapped of the section is made concave. The bar is lapped by pressing the medium facing surface of the bar against a lapping plate rotating while the bar is deformed.
In such a manner, a series of operations is automatically repeated, including determining the throat height and the MR height of each magnetic head element, calculating the deviation of the determined values from the target values, that is, the amounts of lapping required, and lapping the bar while deforming the bar in accordance with the amounts of lapping required. Variations in the throat heights and the MR heights of the magnetic head elements are thereby modified. Finally, the throat heights and the MR heights of the magnetic head elements fall within a specific range.
A lapping apparatus for performing lapping of a bar as described above is disclosed in U.S. Pat. No. 5,620,356. A jig for lapping magnetic heads is disclosed in U.S. Pat. No. 5,607,340. A lapping control apparatus is disclosed in Published Unexamined Japanese Patent Application Heisei 2-95572 (1990) for controlling the throat height through observing the resistance of an MR element.
Another prior-art method of processing the medium facing surface of a bar and separating the bar is the method illustrated in FIG. 7 of U.S. Pat. No. 5,406,694. In this method a block having a specific length and including several rows of slider sections is separated from a wafer. This block is fixed to a specific jig by fixing a surface of the block opposite to the medium facing surface thereof to the jig. Processing is performed on the medium facing surface of the block fixed to the jig. The bar having received processing of the medium facing surface is then separated from the block.
When processing of the medium facing surface and separation of bars are performed through the use of the block as described above, the dimension (hereinafter called the height) of the block, that is, the object to be processed, measured in the direction orthogonal to the medium facing surface changes step by step.
In addition, to obtain more sliders (thin-film magnetic heads) from a circular-plate shaped wafer, it is possible to obtain from the wafer a plurality of types of blocks having different dimensions (hereinafter called lengths) measured in the direction in which slider sections are aligned.
When processing of the medium facing surfaces is performed through the use of the blocks having different heights and lengths as described above, it is required to utilize a jig capable of constantly deforming the medium facing surfaces of the blocks into desired shapes even though the blocks have different heights and lengths.
A prior-art jig designed for processing a bar could be used as a jig for processing the blocks as described above. However, the jig designed for processing a bar is designed to be capable of deforming the bar having specific height and length into a desired shape. Therefore, this jig is not capable of deforming each of blocks into a desired shape, if the objects to be processed are blocks having different heights and lengths, depending on the heights and lengths of the blocks. It is thus difficult to perform processing with precision.
It is an object of the invention to provide a processing jig capable of processing each of a plurality of types of objects with accuracy, the objects having different heights or length, or different heights and length.
A processing jig of the invention is provided for selectively retaining each of a plurality of types of objects to be processed that have different heights or lengths, or different heights and lengths. The jig is fixed to a processing apparatus for processing the objects. The jig comprises: a main body to be fixed to the processing apparatus; a retainer that is long in one direction for retaining each of the objects; a middle load application section coupled to a portion of the retainer located in the middle of the length thereof, a load being applied to the section for deforming the retainer; two end load application sections coupled to portions of the retainer near ends of the length thereof, a load being applied to each of the sections for deforming the retainer; two middle couplers located between the middle load application section and each of the end load application sections, respectively, for coupling the main body to the retainer; and two end couplers for coupling the main body to the ends of the length of the retainer. Along the length of the retainer, a length between the middle of the retainer and each of the ends thereof is greater than a length between the middle of the retainer and each of the end load application sections.
According to the jig of the invention, along the length of the retainer, the length of the retainer between the middle of the retainer and each of the ends thereof is greater than the length of the retainer between the middle of the retainer and each of the end load application sections. As a result, the jig allows each of the objects to be processed to be deformed into a desired shape if the object has a length shorter than the distance between the two end load application sections, or even if the object has a length longer than this distance. When a plurality of types of objects having different heights are to be processed, it is not necessary that the retainer is capable of attaining deformation into a complicated shape. Instead, the retainer is preferably capable of attaining moderate deformation if necessary while basically maintaining the straightness. In the jig of the invention the length between the middle of the retainer and each of the ends thereof is greater than the length between the middle of the retainer and each of the end load application sections. It is thereby possible to moderately deform the long retainer.
According to the jig of the invention, along the length of the retainer, the length between the middle of the retainer and each of the middle couplers may be greater than three sevenths of the length between the middle of the retainer and each of the end load application sections.
According to the jig of the invention, along the length of the retainer, the length between the middle of the retainer and each of the middle couplers may be greater than a half of the length between the middle of the retainer and each of the end load application sections.
According to the jig of the invention, the retainer may include portions each of which is located between the middle of the length thereof and each of the middle couplers, each of these portions having a thickness increasing with increases in the distance from the middle of the length or each of the middle couplers.
According to the jig of the invention, the retainer may include portions each of which is located between each of the ends thereof and each of the middle couplers, each of these portions having a constant thickness.
According to the jig of the invention, each of the end couplers may include: a vertical portion extending in the vertical direction and having an end connected to the main body; a horizontal portion extending in the horizontal direction and having an end connected to one of the ends of the retainer; and a slanting portion extending in a slanting direction and connecting the other end of the vertical portion to the other end of the horizontal portion. In this case, the horizontal portion may have a thickness smaller than the thickness of the retainer.
According to the jig of the invention, a slit may be provided between the retainer and each of the end load application sections, the slit extending from a position closer to the middle of the length of the retainer toward a position closer to one of the ends of the retainer.
According to the jig of the invention, each of the middle couplers may have a length that falls within a range between 150% and 250% of the thickness of a portion of the retainer corresponding to each of the middle couplers.
According to the jig of the invention, each of the objects may be a thin-film magnetic head material made up of at least one row of sections to be sliders each of which includes a thin-film magnetic head element.
Other and further objects, features and advantages of the invention will appear more fully from the following description.